Consider the air over a city to be a box 100 km on a side that reaches up to an altitude of 1.0 km. clean air is blowing into the box along one of its sides with a speed of 4 m/s. suppose an air pollutant with a degradation reaction rate k = 0.2 hr-1 is emitted into the box at a total rate of 10.0 kg/s.
1. if the windspeed in this above problem suddenly drops to 1 m/s, estimate the concentration of the pollutant two hours later.

Two flowing streams of argon gas are adiabatically mixed to form a single flow/stream. one stream is 1.5 kg/s at 400 kpa and 200 c while the second stream is 2kg/s at 500 kpa and 100 ? . it is stated that the exit state of the mixed single flow of argon gas is 150 c and 300 kpa. assuming there is no work output or input during the mixing process, does this process violate either the first or the second law or both? explain and state all your assumptions.

Acompressor receives the shaft work to decrease the pressure of the fluid. a)- true b)- false

Coiled springs ought to be very strong and stiff. si3n4 is a strong, stiff material. would you select this material for a spring? explain.